Process for waterproofing leather



United rates Patent @fifi ce 3,@l9,i33 Patented Jan. 30, E962 3,019,133 PROCESS FGR WATERPRUOFING LEATHER Rudi Heyden and .liirgen Flapper, Dusseidorf, Germany,

assignors to Biihme Fettchemie G.m.b.H., Dusseldorf,

Germany, a corporation of Germany No Drawing. Filed May 14-, 1957, Ser. No. 658,956

Claims priority, application Germany May 14, 1956 8 Claims. (Cl. 111-142) Thisinvention relates to a process for waterproofing leather, and more particularly to a method of improving the hydrophobic properties of leather with the aid of condensation products formed from metal alcoholates and acid high-molecular organic derivatives of phosphoric acid.

We have found that excellent hydrophobic impregnations are obtained in leather if the leather is impregnated with solutions of condensation products formed by metal alcoholates and acid high-molecular organic derivatives of phosphoric acid, especially acid alkyl phosphoric acid esters of high-molecular organic hydroxyl compounds, in organic solvents; the solutions may, if desired, contain small amounts of complex-stabilizing products. The process may be applied to all types of leather, but it is especially suitable for the production of pastel-shade and white suede or grained leather. Depending upon the amounts and conditions, the process imparts water-repellent properties, water-resistance or water-impermeability to the leather.

In tabular form our process for impregnating leather is as follows:

(1) Solution of the polyvalent metal alcoholate in an organic solvent.

(2) Solution of the acid phosphoric acid ester of a high molecular weight organic hydroxyl compound in the solution obtained from step 1.

(3) Heating of the solution to 30 short period of time. (Optional) (4) Solution of an organic complex stabilizing compound in the solution obtained from either step 2 or step 3. (Optional) (5) Impregnating, by soaking, brushing or spraying, the dry leather with the solution obtained from steps 2, 3, or 4.

(6) Drying the leather at 80-90 steaming the leather.

(7) Mechanical treatment of finishing the leather (i.e. brushing, burnishing, etc.).

For the production of the waterproofing agent used in accordance with the invention, primarily aluminum alcoholates, such as aluminum isopropylate, aluminum butylate, aluminum octylate, aluminum dodecylate, or alcoholates of other, preferably low-molecular, organic hydroxyl compounds, the alkyl radicals of which may also comprisesubstituents, such as halogen, may be used as stafting materials. In place of aluminum alcoholates, also alcoholates of other polyvalent metals, such as magnesium alcoholates, titanium alcoholates or zirconium alcoholates, may be used. As a rule, neutral alcoholates are employed, but also those alcoholates may be used which contain basic groups, as well as mixtures of various alcoholates.

Phosphoric acid esters of organic hydroxyl compounds suitable for the production of the condensation products are primarily the corresponding monoalkyl esters with alkyl radicals having at least 6 carbon atoms in the alkyl chain, such as phosphoric acid monooctyl ester, phosphoric acid monododecyl ester, phosphoric acid monooleyl ester, as well as phosphoric acid monoalkylphenol esters wherein the alkyl radicals have from 3 to 18 carbon atoms, phosphoric acid mononaphthenyl ester, phosphoric to 50 C. for a C. or alternatively acid monoabietyl ester, and the like. Furthermore, the corresponding di-esters, if desired in admixture with the monoesters, may be used, as well as those esters the alcohol radicals of which contain substituents or are interrupted by oxygen, sulfur or nitrogen atoms or groups containing oxygen, sulfur and/or nitrogen. In place of the acid phosphoric acid esters, also other high-molecular organic derivatives of phosphoric acids may be used, such as the corresponding acid phosphoric acid alkyl amides, alkyl phosphonic acids, alkyl phosphinic acids and the like.

From these two components condensation products are formed in the presence of inert organic solvents, such as isopropanol, trichloroethylene or toluene, as well as other low-molecular alcohols, aliphatic halogenated hydrocarbons or aromatic hydrocarbons. The formation of these condensation products, which contain for example polyvalent metal monohydroxy alcoholates and phosphoric acid monoalkyl in different molecular proportions, is accomplished by combining solutions of the starting components in the above solvents and thereafter heating the resulting mixture for a short time, if necessary, to temperatures between about 30 and 50 C. The starting components are used in a molar ratio of alcoholate to phosphoric acid ester from 1:05 to 121.5, but other molar ratios may also be used. In place of the finished condensation products, solutions of the stating materials in the solvents may also be used for application to the leather directly. Furthermore, after completion of the condensation reaction, the solvents may also be distilled off and the condensation product may be dissolved in oils, such as mineral oils, which are customarily employed for fat-liquoring the leather.

If necessary, small amounts of complex-stabilizing compounds may be added to the solutions. Products of this type, which are often characterized by the presence of readily exchangeable hydrogen atoms, are, for example, hydroxycarboxylic acid esters, compounds with reactive methylene groups, hydroxy-oxo compounds which are capable of being rearranged into an acidic form, such as acetylacetone and acetoacetic acid ester, as well as oximes and so forth. By the inclusion of such additives into the above-described solutions, the premature decomposition of the solutions or the condensation products through the action of moisture is prevented; the decomposition of the solutions or the condensation products by the moisture may result in undesirable precipitates on the surface of the finished waterproofed leather.

The application of the waterproofing agents according to the invention to the leather may be accomplished by immersion, brushing or especially by spraying. As a rule, solutions are used which contain from 0.5 to 5%, but preferably from 2 to 3%, of the above-mentioned condensation products or mixtures thereof.

The leather is advantageously treated with these solutions in a dry state. Subsequent to the impregnation with the waterproofing agents, the leather is heated for a short period of time, if necessary in the presence of moisture, for example with the aid of steam, whereby the water-repellent efiects are still further improved.

The following examples will further illustrate the present invention and enable other skilled in the art to understand our invention more completely. It is understood, however, that the invention is not limited to the materials and conditions recited in these examples.

Example I 204 parts by weight aluminum isopropylate (1 mol) were dissolved in 500 parts by weight trichloroethylene. A solution of 144 parts by weight of a monoalkyl phonphoric acid ester the alkyl radicals of which contained O C H7 and P Al- O 03.37

whereupon it was ready for use as a waterproofing agent for leather. In order to increase the stability of the solution mixture, 0.1% by weight acetoacetic acid ester or acetylacetone may be added thereto. In place of the trichloroethylene, benzene or toluene may also be used as the solvent. White and pastel-shade mineraland synthetic-tanned suede and nubuk leathers were treated with the above solution mixture, which had been adjusted to a content of condensation product of 3% by weight by the addition of further trichloroethylene. The waterproofing solution was applied to the leather with the aid of a spray gun under a pressure of 4 atmospheres gauge, passing over the leather from two to three times in crisscross fashion. The impregnated leather was dried in the customary fashion. An especially good hydrophobic effect was obtained, however, when the impregnated leather was dried at temperatures between about 80 and 90 C. The leather thus obtained had a pleasant, soft feel and excellent water-repellent properties.

Example 11 and O-Al

CraHnO Was formed. Light-colored, aniline-dyed split cowhide was impregnated with this solution, which had previously been adjusted to a condensation product content of 3% by weight by the addition of more benzene. The solution was applied to the cowhide with the aid of a spray gun at a pressure of about 4 atmospheres gauge, passing over the leather twice in crisscross fashion. Thereafter,

obtained. The same effect was therewith in the manner the leather was dried in the customary fashion and brushed. The impregnated leather thus obtained was water-repellent and had a pleasant, soft feel.

Example 111 204 parts by weight aluminum isopropylate (1 mol) were dissolved in 500 parts by weight trichloroethylene. 400 parts by weight monododecyl phosphate (1.5 mols) dissolved in 500 parts by weight trichloroethylene were added to the solution, and the resulting solution mixture was stirred and heated to about 60 C. for about 3 minutes, whereby a trichloroethylene solution of a condensation product mixture having the structural formula on o was formed. In this form the solution was ready for use as a waterproofing agent for leather. However, alternatively, the solvent may also be distilled off and may be replaced by a suitable mineral oil, for example spindle oil having a viscosity of about 4 E For purposes of stabilization, the solution was also modified with 0.1% by weight of acetoacetic acid ester. Dark-colored leather was sprayed with this solution in the manner described in the preceding example; the solution had previously been adjusted to a condensation product content of 3% by weight. After drying the impregnated leather in the customary fashion, an excellent hydrophobic effect was obtained when the leather was fat-liquored with a solution of the above condensation product in mineral oil in the usual fashion.

Example IV 204 gm. aluminum isopropylate (1 mol) were dissolved in 500 gm. trichloroethylene. A solution of 205 gm. of the monophosphoric acid ester of octylphenol (0.7 mol) in 1000 gm. trichloroethylene was added to the aluminum isopropylate solution and the resulting solution mixture was heated to about 40 C. for about 6 minutes, whereby a trichloroethylene solution of a condensation product mixture having the structural formulas O. CeHi. CsH -y was formed. After adjusting the solution to a condensation product content of about 3% by weight by the addition of more trichloroethylene, leather was impregnated described in Example I. A leather with excellent Water-repellent properties was ob:

' tained.

228 gm. titanium tetraethylate (1 mol) were dissolved in 750 gm. benzene. A solution of 144 gm. monoalkyl phosphoric acid esters with alkyl radicals having from 12 to 18 carbon atoms (0.7 mol) in 750 gm. benzene was added to the above solution accompanied by stirring. For purposes of stabilization, 5 gm. of acetylacetone were added to the resulting solution mixture. Thereafter, the solution was adjusted to a condensation product content of 3% by weight by the addition of more benzene. The

solution contains a mixture if condensation products of the formulas P Ti nzHuO \O/ ca s and OC'zHg o'ri 0 01H, 2 5

P 002E; 018E370 0'Ti 0CgH5 Apparel leather was impregnated with this solution by the spray method and subsequently dried at 40 to 60 C. in accordance with the procedure described in Example I. The leather thus obtained exhibited excellent water-repellent properties.

While we have illustrated certain specific embodiments of our invention, it will be readily apparent to those skilled in the art that the present invention is not limited to these specific embodiments, and that various changes and modifications may be made without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. The process of waterproofing leather which comprises impregnating the leather With an inert organic solvent containing (1) from 0.5 to about 5% of a waterinsoluble condensation product formed by a condensation reaction between about one mol of an alcoholate of a polyvalent metal selected from the group consisting of aluminum, magnesium, titanium and zirconium, and from about 0.5 to about 1.5 mols of a diacid phosphoric acid monoester of a high-molecular weight organic hydroxyl compound selected from the group consisting of alkanols having from 6 to 18 carbon atoms and alkylphenols having from 3 to 18 carbon atoms in the alkyl chain and (2) a small amount of a complex-stabilizing compound having a readily exchangeable hydrogen atom and drying said leather.

2. A waterproof leather process of claim 1.

3. The process of waterproofing leather which comprises impregnating the leather with a leather fat-liquoring oil having dissolved therein (1) from 0.5 to about 5% of a water-insoluble condensation product formed by a condensation reaction between about one mol of an alcoholate of a polyvalent metal selected from the group consisting of aluminum, magnesium, titanium and zirconium, and from about 0.5 to about 1.5 mols of a diacid phosphoric acid monoester of a high-molecular weight organic hya prepared according to the droxyl compound selected from the group consisting of alkanols having from 6 to 18 carbon atoms and alkylphenols having from 3 to 18 carbon atoms in the alkyl chain and (2) a small amount of a complex-stabilizing compound having a readily exchangeable hydrogen atom and drying said leather.

4. The process of waterproofing leather as in claim 3 wherein said leather fat-liquoring oil is a mineral oil.

5. The process of waterproofing leather, which comprises impregnating the leather With an inert organic solvent containing (l) a water-insoluble condensation product formed by a condensation reaction between an aluminum alcoholate and a monoester of phosphoric acid with a high-molecular weight organic hydroxyl compound selected from the group consisting of alkanols having from 6 to 18 carbon atoms and alkyl phenols having from 3 to 18 carbon atoms in the alkyl chain and (2) a small amount of a complex-stabilizing compound having a readily exchangeable hydrogen atom and drying said leather.

6. The process of claim 5 wherein said condensation product is applied to the leather in the form of a solution in an inert organic solvent, and the solvent is evaporated.

7. The process of Waterproofing leather which comprises applying to the leather a solution of an inert organic solvent containing dissolved therein (1) from 0.5% to about 5% of a Water-insoluble condensation product formed by a condensation reaction between about one mol of aluminium isopropylate and from about 0.5 to about 1.5 mols of a monoalkyl ester of phosphoric acid, said alkyl radical containing from 6 to 18 carbon atoms, and (2) a small amount of a complex-stabilizing compound having a readily exchangeable hydrogen atom, evaporating the solvent, and drying said leather between to C.

8. The process of waterproofing leather which comprises applying to the leather a solution of a fat-liquoring mineral oil containing dissolved therein l) a Water-insoluble condensation product formed by a condensation reaction between about one mol of aluminum isopropylate and from about 0.5 to about 1.5 mols of a monoalkyl ester of phosphoric acid, said alkyl radical containing from 6 to 18 carbon atoms and (2) a small amount of a complexstabilizing compound having a readily exchangeable hydrogen atom and heating said leather between 80 and 90 C.

References Cited in the file of this patent UNITED STATES PATENTS 1,645,642 Blackadder Oct. 18, 1927 2,769,733 Pool Nov. 6, 1956 2,772,988 Plapper et a1 Dec. 4, 1956 2,774,690 Cockett et al Dec. 18, 1956 2,801,190 Orthner et a1 July 30, 1957 2,872,351 Wedell Feb. 3, 1959 

1. THE PROCESS OF WATERPROOFING LEATHER WHICH COMPRISES IMPREGNATING THE LEATHER WITH AN INERT ORGANIC SOLVENT CONTAINING (1) FROM 0.5 TO ABOUT 5% OF A WATER INSOLUBLE CONDENSATION PRODUCT FORMED BY A CONDENSATION REACTION BETWEEN ABOUT ONE MOL OF AN ALCOHOLATE OF A POLYVALENT METAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, MAGNESIUM, TITANIUM AND ZIRCONIUM, AND FROM ABOUT 0.5 TO ABOUT 1.5 MOLS OF A DIACID PHOSPHORIC ACID MONOESTER OF HIGH-MOLECULAR WEIGHT ORGANIC HYDROXYL COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKANOLS HAVING FROM 6 TO 18 CARBON ATOMS AND ALKYLPHENOLS HAVING FROM 3 TO 18 CARBON ATOMS IN THE ALKYL CHAIN AND (2) A SMALL AMOUNT OF A COMPLEX-STABILIZING COMPOUND HAVING A READILY EXCHANGEABLE HYDROGEN ATOM AND DRYING SAID LEATHER. 